The present invention relates generally to the field of photographic developing equipment, and more particularly, is directed to a film drying system designed for use with automatic film developing machinery.
Small, self-contained, automatic X-ray and other film processing machinery has become increasingly more popular in use due to the ability of such equipment to satisfactorily perform, thereby eliminating the large capital expenditures which would otherwise be required to construct extensive dark room facilities. The present invention relates to film drying rollers which position at the delivery end of such self-contained film developing apparatus and which are employed to dry the film in an improved manner. The invention is equally applicable for use with all types of automatic photographic processers such as development equipment suitable for use with x-ray, graphic arts, commercial film, etc. The device is compatible for use in conjunction with presently available self-contained film processing units and greatly improves over all known prior art types of film dryer systems in efficiency, quality, speed of operation and extremely low installation and maintenance cost factors.
The self-contained, automatic film processing equipment of the type contemplated for use with the novel drying rollers of the present invention comprise a plurality of adjacent processing tanks, each of which is provided with a separate rack assembly which includes pluralities of pairs of driving and driven rollers. The rollers contact the film surface to drive the exposed x-ray or other type of film through the various processing tanks which conventionally contain the usual developers, fixers and washers to positively and automatically develop exposed x-ray or other type of film in accordance with well known principles of automatic film developing apparatus.
It is known to employ separate, horizontally juxtaposed rack assemblies for the developer tank, the fixer tank and the wash tank to automatically feed the exposed x-ray or other type of film directly through the tank and between the tanks in an automatic manner. The prior art rack assemblies direct the film downwardly into each respective tank, upwardly through each tank, and between tanks in a manner to introduce the film into the next adjacent tank. Following completion of the developing operations, the film is directed from the automatic processing equipment by a film delivery system for drying in a dryer chamber and then for delivery of the finished product in a conventional manner. Prior to exiting from the equipment, it is necessary to carefully dry the film to prevent damage to the emulsion. In this regard, various types of blowers, baffles and more or less complicated air directional apparatus have been employed to guide the air currents to impinge upon the film surface for optimum overall drying operations. All of the prior art dryer systems of which we are familiar are quite costly in construction and expensive in maintenance, thereby adding to the overall initial cost of the machine and to the operating costs after installation.
Additionally, the presently available dryers have proved deficient in removing droplets of moisture which remain upon the film surface after the film is directed through the wash tank. Most film is fabricated of acetate, polyester or other plastic based emulsion which is characterized by the presence of extremely high surface tension. Due to this surface tension, liquid remains upon the film surface in the form of small, round droplets which prior works in the art have found extremely difficult to remove. Some workers have tried to blow the droplets off of the plastic film sheet. Such procedures have proved unsatisfactory in that the dryer section fan pressure forces blow the droplets over the film surface in a manner which tends to leave a track on the emulsion surface, thereby actually creating a change in the emulsion surface and resulting in a deficient final product. Other prior workers in the art have attempted to solve the surface tension problem by placing a wetting agent in the fixative tank in an attempt to break down the surface tension. To date, the addition of the wetting agent has not significantly reduced the surface tension to a level satisfactory to eliminate the moisture droplet problem.